[1] About EPEL repo: http://fedoraproject.org/wiki/EPEL
Note: It is possible that yum install may not find any package when installing a php- or http- extensions. We may have to exclude php* and http* from yum.conf (usually in /etc/yum.conf) by renaming php* and http* and then running 'yum install'. This makes it work. Reference: Install PECL